1. Field of the Invention
The present invention relates to an illumination optical unit for an endoscope that radiates a part to be observed in a subject with illumination light in order to observe the inside of the subject, and a method of manufacturing the same.
2. Description of the Related Art
In the related art, diagnosis using an endoscope is widely prevalent in the medical field. The endoscope includes, at the distal end of an insertion part to be inserted into a subject, an observation window for incorporating image light of the subject and an illumination window for radiating illumination light toward the subject. The endoscope is connected to a light source device via a cord or a connector.
The light source device has a light source for supplying the illumination light for illuminating the inside of the subject to the endoscope. The illumination light from the light source is guided to the distal end of the insertion part by a light guide inserted through the endoscope. In the related art, a white light source, such as a xenon lamp or a halogen lamp, has been used as the light source that constitutes the light source device. However, a light source device using a laser beam source has recently began to be used instead of this white light source.
An endoscope in which a laser beam supplied from the light source device using this laser beam source is guided to the distal end of the insertion part by the light guide, and a fluorescent body arranged on the distal side end of the light guide is excited by the laser beam to emit light so as to radiate a body cavity with white illumination light is described in JP2007-20937A. In the endoscope described in JP2007-20937A, the fluorescent body is provided integrally with a cover glass, the distal end portion of the insertion part is formed with a through hole to which the light guide and the cover glass are attached, and the fluorescent body attached to the distal end portion of the insertion part along with the cover glass is arranged at the emission end of the light guide.
Additionally, the endoscope is required to radiate a higher intensity of illumination light. Therefore, a reflective film with high reflectivity may be provided around the fluorescent body in order to efficiently use the excited and emitted light as the illumination light. As this reflective film with high reflectivity, it is known that a metal film of silver, aluminum, or the like is suitable.